Optical touch panel having reduced number of elements

ABSTRACT

An optical touch panel includes a plurality of light-emitting elements, reflectors for reflecting lights from the plurality of light-emitting elements, and a plurality of light-receiving elements for receiving reflected lights from the reflectors. The plurality of light-emitting elements and the plurality of light-receiving elements are arranged alternately along two adjacent sides of a rectangular position-detecting surface, and the reflectors are arranged along the other two adjacent sides of the position-detecting surface, respectively. A drive controller causes the plurality of light-emitting elements to light in a predetermined order to thereby cause ones of the light-receiving elements arranged on opposite sides of each of the plurality of light-emitting elements to receive reflected lights from the reflectors. Hollow cylinders opposed to the respective light-receiving elements inhibit lights other than the reflected lights reflected by the reflectors from being incident on the plurality of light-receiving elements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved optical touch panel.

2. Description of the Prior Art

FIG. 4 shows the construction of a conventional optical touch panel.

The optical touch panel 101 has a plurality of light-emitting elements110 arranged along two adjacent sides of a rectangularposition-detecting surface 150 and a plurality of light-receivingelements 130 arranged along the other two sides of the same such thatthe light-emitting elements 110 are opposed to the respectivelight-receiving elements 130 with the position-detecting surface 150therebetween.

A control block 140 causes the light-emitting elements 110 to lightsequentially from left to right and from top to bottom as viewed in FIG.4, and causes the light-receiving elements 130 to receive lights fromthe respective light-emitting elements 110 opposed thereto.

In the optical touch panel 101, optical paths are formed on theposition-detecting surface 150 in a grid pattern.

When an object 170 lies in a position shown in FIG. 4, the object 170blocks some optical paths to thereby hinder lights from thecorresponding light-emitting elements 110 from reaching light-receivingelements 130 opposed to the light-emitting elements 110. As a result,the control block 140 detects the position (two dimensional coordinates)of the object 170 based on information of received lights from thelight-receiving elements 130.

In the above optical touch panel 101, however, it is required to arrangeelements 110, 130 along the four sides of the rectangularposition-detecting surface 150, and hence it takes a lot of time forestablishing wire connections of the elements.

To solve the problem, another optical touch panel constructed as belowwas proposed.

FIG. 5 shows the construction of this prior art optical touch panel.

The optical touch panel 201 is comprised of light-emitting elements 210,two reflectors 220 for reflecting lights from the light-emittingelements 210, and light-receiving elements 230 for receiving thereflected lights from the reflectors 220.

The light-emitting elements 210 and the light-receiving elements 230 arealternately arranged along two adjacent sides of a rectangularposition-detecting surface 250, and the reflectors 220 are arrangedalong the other two adjacent sides of the rectangular position-detectingsurface 250.

When an object 270 lies in a position shown in FIG. 5, the object 270blocks some optical paths to thereby hinder lights from the reflectors220 from reaching the light-receiving elements 230 opposed to the object270. As a result, a control block 240 detects the position of theobstacle 270 based on information of received lights from thelight-receiving elements 230.

This optical touch panel makes it possible to simplify wiring, comparedwith the FIG. 4 conventional touch panel.

However, the FIG. 5 optical touch panel uses a pair of elements (i.e. alight-emitting element 210 and a light-receiving element 230) per oneoptical path, so that it is required to provide numerous light-emittingand light-receiving elements, which results in an increase inmanufacturing costs.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an optical touch panelhaving a construction which makes it possible to decrease the number ofelements, thereby reducing manufacturing costs.

To attain the above object, the present invention provides an opticaltouch panel including a plurality of light-emitting means, reflectormeans for reflecting lights from the plurality of light-emitting means,and a plurality of light-receiving means for receiving reflected lightsfrom the reflector means, the plurality of light-emitting means and theplurality of light-receiving means being arranged alternately along twoadjacent sides of a rectangular position-detecting surface, thereflector means being arranged along each of other two adjacent sides ofthe position-detecting surface.

The optical touch panel according to the invention is characterized bycomprising:

control means that causes the plurality of light-emitting means to lightin a predetermined order to thereby cause ones of the plurality oflight-receiving means arranged on opposite sides of each of theplurality of light-emitting means to receive reflected lights from thereflector means; and

blocking means that inhibits lights other than the reflected lightsreflected by the reflector means from being incident on the plurality oflight-receiving means.

According to this optical touch panel, when an object lies on one of twooptical paths simultaneously formed in a manner extending from onelight-emitting means to corresponding two light-receiving means, i.e.two light-receiving means arranged on respective opposite sides of theone light-emitting means, one of the two light-receiving means on oneside of the lit light-emitting means receives a reflected light from thereflector means, whereas the other of the two light-receiving means onthe other side does not receive the reflected light. These results aredelivered as received-light information from the two light-receivingmeans to the control means. The control means detects the position ofthe object based on received-light information delivered from thelight-receiving means arranged along the two sides of theposition-detecting surface. It should be noted that lights reflected offthe object on the position-detecting surface are blocked by the blockingmeans and inhibited from being incident on the light-receiving means,and therefore it is possible to detect the position of the objectwithout any error.

Preferably, the blocking means is formed by a plurality of hollowcylinders opposed to light-receiving surfaces of the plurality oflight-receiving means, respectively.

According to this preferred embodiment, lights from optical paths otherthan predetermined optical paths are blocked by the peripheral wall ofeach hollow cylinder and inhibited from being incident on thelight-receiving surfaces of the light-receiving means.

Alternatively, the blocking means is formed by plates formed with aplurality of through holes opposed to light-receiving surfaces ofrespective corresponding ones of the plurality of light-receiving means.

According to this preferred embodiment, lights from optical paths otherthan predetermined optical paths are blocked by the plates and inhibitedfrom being incident on the light-receiving surfaces of thelight-receiving means.

More preferably, the optical touch panel further comprises a pluralityof condensing lenses for each condensing a light emitted from acorresponding one of the plurality of light-emitting means such that thecondensed light is directed in a predetermined direction.

According to this preferred embodiment, a light emitted from each of theplurality of light-emitting means is condensed such that the condensedlight is directed in a predetermined direction and then reflected by thereflector means to be incident on the associated light-receiving means.

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription taken in conjunction with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of an optical touchpanel according to a first embodiment of the invention;

FIG. 2 is a block diagram showing the construction of an optical touchpanel according to a second embodiment of the invention;

FIG. 3 is a block diagram showing the construction of an optical touchpanel according to a third embodiment of the invention;

FIG. 4 is a block diagram showing the construction of a conventionaloptical touch panel; and

FIG. 5 is a block diagram showing the construction of anotherconventional optical touch panel

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in detail with reference to drawingsshowing preferred embodiments thereof.

FIG. 1 shows the construction of an optical touch panel according to afirst embodiment of the invention.

The optical touch panel 1 is comprised of light-emitting elements(light-emitting means) 10, reflectors (reflector means) 20,light-receiving elements (light-receiving means) 30, and a drivecontroller (control means) 40.

The light-emitting elements 10 and the light-receiving elements 30 arearranged alternately along two adjacent sides (in respective X and Ydirections) of a frame, not shown, which holds a rectangularposition-detecting surface 50.

The light-receiving elements 30 are arranged at locations backward ofthe light-emitting elements 10, i.e. rightward of the light-emittingelements 10 arranged along the right side of the frame and downward ofthe light-emitting elements 10 arranged along the lower side of theframe, as viewed in the figure. Hollow cylinders (blocking means) 60 areeach arranged such that an end face thereof is opposed to alight-receiving surface 31 of the corresponding light-receiving element30.

Therefore, lights reflected off an object 70 on the position-detectingsurface 50 are blocked by the wall of each hollow cylinder 60, so thatthe light-receiving elements 30 can receive only lights reflected by thereflectors 20.

The length and inner diameter of each hollow cylinder 60 are set suchthat the hollow cylinder 60 allows lights reflected by the reflector 20to be incident on the light-receiving element 30, but blocks lightsreflected off the object 70 and lights directly emitted from adjacentlight-emitting elements.

Each light-emitting element 10 is comprised e.g. of a light-emittingdiode, while each light-receiving element 30 is comprised e.g. of a pinphotodiode or a phototransistor.

The light-emitting element 10 includes e.g. an npn transistor and anemitter resistor and is driven by a signal from the drive controller 40.

The light-receiving element 30 receives reflected lights in response toa signal from the drive controller 40.

The light-receiving element 30 includes e.g. a comparator, not shown. Areceived-light level of a reflected light received by thelight-receiving element 30 is compared with a predetermined thresholdlevel by the comparator, and a signal generated by the comparator isdelivered to the drive controller 40.

The comparator delivers the signal having a predetermined logical level(e.g. an H level) when the received-light level has reached thethreshold level.

The reflectors 20 are arranged along the other two sides of theposition-detecting surface 50, respectively. The reflectors 20 are eachformed by coating a base plate formed e.g. of ABS resin (acrylonitrilebutadiene styrene terpolymer) with multilayer films having highreflectances at respective different wavelengths.

The drive controller 40 delivers signals to the light-emitting elements10 and the light-receiving elements 30 in response to instructions froma drive interface, not shown, to cause the light-emitting elements 10 tolight in a predetermined order (e.g. by lighting one by one in asequential order or by simultaneously lighting a plurality of alternateones at each time), and light-receiving elements 30 arranged on theopposite (i.e. both) sides of each of the lit light-emitting elements 10to receive reflected lights from the corresponding one of the reflectors20. Then, the drive controller 40 informs the drive interface of theposition of the object 70 detected based on the output signals from thecomparators of the respective light-receiving elements 30.

The position of the object 70 is detected as X and Y coordinatesdetermined from the positions of light-receiving elements 30 deliveringoutput signals each having an L level.

The construction described above enables the optical touch panel 1 todetect the object 70 on the position-detecting surface 50.

According to the above embodiment, since the optical touch panel 1 isconstructed such that light-receiving elements 30 located on theopposite, i.e. both sides of each light-emitting element 10 receivereflected lights, the number of the light-emitting elements 10 and thelight-receiving elements 30 can be reduced sharply from the number ofthose in the prior art, which contributes to reduction of manufacturingcosts.

Further, since lights reflected off the object 70 can be blocked by thewall of each hollow cylinder 60, it is possible to prevent erroneousdetection from being caused by other lights than the reflected lightsfrom the reflectors 20.

FIG. 2 shows the construction of an optical touch panel according to asecond embodiment of the invention. Component parts and elementscorresponding to those of the first embodiment are indicated byidentical reference numerals, and description thereof is omitted.

The second embodiment is distinguished from the first embodiment in thatplates (blocking means) 65 each formed with through holes 65 a eacharranged in a manner opposed to a light-receiving surface 31 of acorresponding light-receiving element 30 are used in place of the hollowcylinders 60.

According to the second embodiment, since the construction of theblocking means is simpler than that of the first embodiment,manufacturing of the optical touch panel is facilitated, which makes itpossible to produce the optical touch panel at lower costs than that ofthe first embodiment.

FIG. 3 shows the construction of an optical touch panel according to athird embodiment of the invention. Component parts and elementscorresponding to those of the first embodiment shown in FIG. 1 areindicated by identical reference numerals, and description thereof isomitted.

The third embodiment is distinguished from the first embodiment in thatcondensing lenses 15 are arranged in front of respective light-emittingelements 10 in the direction of light emission. Each condensing lens 15condenses light emitted from the corresponding light-emitting element 10such that the condensed light is directed in a predetermined direction.

In this embodiment, since the divergence of light emitted from eachlight-emitting element 10 is reduced by the condensing lens 15, so thateach hollow cylinder 60 is made shorter i.e. smaller in length than thatof the first embodiment.

The third embodiment can provide the same effects as obtained by thefirst embodiment. Further, according to the third embodiment, since eachhollow cylinder 60 is shorter as described above, it is possible to makethe size of the optical touch panel smaller than that of the opticaltouch panel of the first embodiment.

Although in the first and third embodiments, the hollow cylinders 60 areformed separately from a frame holding the light-emitting elements 10and the light-receiving elements 30, this is not limitative but thehollow cylinders 60 may be integrally formed with the frame.

It is further understood by those skilled in the art that the foregoingare preferred embodiments of the invention, and that various changes andmodification may be made without departing from the spirit and scopethereof.

What is claimed is:
 1. An optical touch panel comprising: a plurality oflight-emitting means for emitting light, reflector means for reflectingthe light emitted by said plurality of light-emitting means, a pluralityof light-receiving means for receiving the light reflected by saidreflector means, said plurality of light-emitting means and saidplurality of light-receiving means being arranged alternately along eachof first and second adjacent sides of the rectangular position-detectingsurface, said reflector means being arranged along each of third andfourth adjacent sides of said position-detecting surface, control meansfor causing said plurality of light-emitting means to light in apredetermined order to thereby cause respective ones of said pluralityof light-receiving means arranged on opposite sides of each of saidplurality of light-emitting means to receive the light reflected by saidreflector means, and blocking means for inhibiting light other than thelight reflected by said reflector means from being incident on saidplurality of light-receiving means, wherein said blocking meanscomprises a plurality of hollow cylinders opposed to light-receivingsurfaces of said plurality of light-receiving means, respectively.
 2. Anoptical touch panel according to claim 1, wherein said blocking meanscomprises plates formed with a plurality of through holes opposed tolight-receiving surfaces of respective corresponding ones of saidplurality of light-receiving means.
 3. An optical touch panel accordingto claim 1, further comprising a plurality of condensing lenses each forcondensing light emitted from a corresponding one of said plurality oflight-emitting means such that the condensed light is directed in apredetermined direction.
 4. An optical touch panel according to claim 1,further comprising a plurality of condensing lenses each for condensinglight emitted from a corresponding one of said plurality oflight-emitting means such that the condensed light is directed in apredetermined direction.
 5. An optical touch panel according to claim 2,further comprising a plurality of condensing lenses each for condensinglight emitted from a corresponding one of said plurality oflight-emitting means such that the condensed light is directed in apredetermined direction.